The present invention relates to the locking and restraining of pieces of freight in the cargo space of aircraft and including so-called locking dogs of the fold down variety, so that they can be rolled over by freight.
Locking dogs of the type to which the invention pertains is usually pivotally mounted in a case, frame or the like, which in turn is inserted in a rail, there being a grid of such rails in the floor of the cargo space of the aircraft. The locking dogs of the type to which the invention pertains are sometimes called YZ restrainers, and they are provided to hold pallets and/or containers in a particular position within the cargo space of the aircraft whereby "holding" is to mean the exertion of restraining action for holding the pallet or container against lateral displacements as well as against vertical ones. The locking dogs are therefore constructed to have a latch or locking element or members projecting from the respective mounting case or frame and gripping over ledges and/or other projections of the piece of cargo to be restrained.
The rails in the bottom of the freight space hold these locking dogs which are mounted thereto by means of rapid action locks which can be easily unlocked in order to change the distribution pattern of the locking dogs in the aircraft. One has to adapt this pattern, of course, to the size of the pieces of freight. As stated the locking elements are to be of the fold down type, which means they have, for example, a projecting or fold up position for acting in a restraining capacity as against lateral displacement in one direction which is equivalent to a fold up effecting force direction, while a force when exerted in the opposite direction, for example, by an approaching piece of cargo, causes the latch and locking element to fold down.
The latch elements and locking dogs provided in the past are disadvantaged by the fact that a fold down for purposes of permitting the passage of a piece of cargo in a direction which normally is restrained by the folded up locking element, is rather complicated to attain, therefore, an electrical control or a manual control or a combination of both is required in order to hold the lock element down in this instance and to permit its erection after the piece of cargo has passed. Moreover, this operation is frequently a selective in one that only some lock elements are to be folded down while others are to be maintained in their locking position. It was found that the known locking dogs are not adequate for this purpose.